Among plastics, thermosetting resins, because these are excellent in the electric insulating property, heat resistance and mechanical strength, are widely used as materials for use in electric and electronic components, automobile components and the like. The thermoplastic resin, when it is once cured, does neither soften nor fuse, nor is dissolved in a solvent; accordingly, it is technically difficult to recycle a valuable chemical raw material from the cured matter. However, in recent years that necessity of environment preservation and formulation of a resource circulation type society are being studied, the recycle of the thermosetting resins is under various studies.
In order to overcome the problems, patent document 1 discloses a technology in which, while a phenol resin is dissolved in phenol that is a constituent monomer of the resin to decompose to a low molecular compound such as phenol, an organic filler is recovered. Furthermore, patent document 2 discloses a technology where alcohol under a supercritical or subcritical state is brought into contact with a phenol resin to decompose to and recover phenol, and further describes to the effect that, from the recovered phenol, through a reaction with formaldehyde, a phenol resin may be formed.    [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-054138    [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-055468